I tried to add it as javascript in ACP (applied in all the pages), tried to call raw .js link in my <head> tags by <script url...> or even tried to add whole code to header in <script type...> tags. Failed.

I applied it to JS codes management in all the pages, but it threw an error because the person who wrote it forgot a semi-colon at line 561 which causes an error when minified by Forumotion's JS management.

Code:

deltaY = Math.abs(deltaY);

Try adding the code below into JS codes management, it should work.

Code:

//// SmoothScroll for websites v1.3.8 (Balazs Galambosi)// Licensed under the terms of the MIT license.//// You may use it in your theme if you credit me. // It is also free to use on any individual website.//// Exception:// The only restriction would be not to publish any // extension for browsers or native application// without getting a written permission first.//